But before the Syrian civil war, which started six years ago, its population was only 4.5 million.

The country now hosts more than one million refugees registered by the UN High Commissioner for Refugees, also known as UNHCR.

“Of that number, 500,000 are school aged children, but only half of them are in school,” said Bassam Khawaja, Human Rights Watch researcher for Lebanon. “So, 250,000 Syrian children, about a quarter of a million are currently not getting a formal education in Lebanon.”

As of May 2015, the government instructed UNHCR to stop registering Syrian refugees.

And the number of children out of school could be even higher.

“Aside from the registered Syrian refugees, there is a whole other group of Syrians in the country who are not registered who the government estimates to be about 500,000 people,” added Khaja. “So, we don’t know how many of those 500,000 are school aged children.”

Lebanon is not a signatory to the United Nations 1951 Refugee Convention, and the country doesn’t have national legislation that deals with refugees.

The government currently offers Syrians temporary protection, and refers to them as “displaced.”

Refugee children can enroll in schools without proof of legal status, however, stringent residency regulations remain a major barrier for Syrian families.

One strategy the Lebanese government has adopted to cope with the mass influx of refugees in public schools is the “second shift,” which essentially created afternoon classes in public schools only for Syrians.

Despite this, bullying and racism at second shift schools against Syrians has discouraged many refugee children from going to school.

Human Rights Watch estimates that at least 750,000 Syrian children are out of school in Turkey, Lebanon, and Jordan.

And rights groups warning that these children risk becoming a lost generation.